The described embodiments relate generally to batteries and in particular to preventing thermal runaway propagation within a battery.
Cells in a battery may fail in the form of an exothermal process called thermal runaway. A thermal runaway process in a cell may be caused by manufacturing defects, mishandling or abuse of cells or any factor that raises a cell's temperature, or exposes the cell to high temperatures from an external source. The high temperatures often cause an increase in reaction rates in the cells, thereby causing a further increase in their temperature and therefore a further increase in the reaction rate. As a result of this runaway process, cells in a battery release a large amount of heat into areas surrounding the cell.
Multiple cells are often needed to reach higher voltages and store sufficient energy to make the battery effective for its intended use. Since cells of a battery are often packed very closely together, if one cell in a part of an assembly of cells experiences thermal runaway, the high temperature of that failed cell can trigger thermal runaway of nearby cells. Such a process may cause the nearby cells to release heat and propagate the thermal runaway process throughout the remaining cells in the battery, causing a cascading failure of the battery and releasing a large amount of energy.